Slow RAID & system performance on large file write

Question

I'm moving a large VHD file to a new VM host over the network. I've checked and double checked every point of bottlenecking here and it is 100% the server doing the writing causing an issue.

It's a RAID-10, 4x1TB Western Digital Enterprise drives on a Dell PERC6/i. It's strip size it set to 64, and and write back is enabled. I just checked the array and individual drive status in the controller BIOS and everything is healthy.

When I start the transfer speeds are nearly saturating the gigabit connection, before the cache fills and has to be written directly to disk (I think that's what is happening). Then speeds are about 10MB/s and it's looking like a ~8 hour transfer for 300GB.

I've updated the 6/i firmware, Windows is completely updated, (Server 2012R2).

EDIT: Also the new host machine (receiving the transfer) becomes so sluggish it is almost un-usable. Once the transfer is cancelled it goes back to normal.

Replicate the problem using a strictly local disk I/O benchmark. — David Schwartz, Mar 26 '16 at 01:13
@DavidSchwartz I did it with a USB copy, now trying to replicate with a copy on the same VD. Will update. — xGlorify, Mar 26 '16 at 01:15
@DavidSchwartz same issue. Performance is good initially, then slows down to about 10MB/s. — xGlorify, Mar 26 '16 at 01:32

score 0 · Answer 1 · answered Mar 26 '16 at 07:43

0

This can be related to cache-trashing. Try to set the disk's controller cache in write-through mode. Does this change anything?

answered Mar 26 '16 at 07:43

shodanshok

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Slow RAID & system performance on large file write

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